深水气井测试水合物生成的预测及防治

深水气井测试时,海水段较长且温度较低,天然气容易在泥线至海平面之间形成水合物,堵塞井筒,导致测试失败。建立深水气井井筒温度-压力模型,模拟南海西部某深水探井测试制度,求解得到井筒流体温度、压力分布;对该区域天然气样进行水合物生成实验,得到天然气水合物生成临界条件。结合测试模拟结果,认为温度是影响水合物生成的主要因素且常规测试过程中该井会在泥线附近生成水合物。隔热油管能够降低井筒整体传热系数,提升流体温度,模拟显示采用隔热油管后流体温度整体升高30℃左右,不同产量下测试均不会生成水合物,能够保证测试顺利进行,该井实测情况也证实了这一预测。实测不同产量下井口温压数据与模拟结果对比,误差均小于5%,证明了模型的准确性,表明该方法能够为深水气井测试过程中水合物预测和防治提供依据。     

气井用水合物自生热解堵剂解堵效果数值模拟

在气井生产后期井筒水合物堵塞井筒现象频发,井筒水合物解堵越发重要.针对气井井筒水合物解堵问题,根据气井水合物堵塞过程和某型自生热解堵剂特性,建立了天然气水合物堵塞段分解速率数学模型和传热数学模型.开展了井筒内水合物解堵过程仿真模拟计算,获得了不同解堵剂浓度解堵过程中井筒内温度、水体积分数等参数的分布云图,得到了不同自生...     

井筒水合物的防治措施探讨

如何根据温度的变化比较准确的预测出水合物在气井井筒中的形成位置,对优化气井生产、防止水合物的产生,高效开发气田都具有重要的意义,因此本文主要就井筒水合物的防治措施进行分析,最后提出应该根据油气田实际情况合理选择井筒水合物的防治。     

深水气井测试条件下井筒水合物生成及浅层水合物分解的环空保护液导热系数

针对南海海域可能钻遇浅层水合物,且在深水井测试过程中井筒生成天然气水合物造成井筒堵塞的难题,从环空保护液的角度出发,以南海某深水气井为例,采用数值模拟方法,研究深水气井测试时不同产量下不同环空保护液导热系数对井筒生成水合物和浅层水合物分解的影响。结果表明：环空保护液导热系数越低,井筒生成水合物的临界测试产量越低,当环空保护液导热系数低至0.10 W/(m·℃)时,可满足产量5×10⁴ m³/d,井筒内不生成水合物;随着环空保护液导热系数降低,井筒外缘温度随之降低,浅层水合物越不容易发生分解;现场测试产量下的井口温度与模拟结果误差均小于5%,验证了计算模型的可行性。     

天然气水合物形成条件的预测

天然气水合物的形成对天然气开采与集输都会产生极大的影响，本文介绍了影响天然气水合物形成的主要条件与次要条件，以及目前预测天然气水合物形成条件的进展情况，文中着重介绍了国外在预测高压条件下（８０～１００ＭＰａ时）气井井筒及海底集气管线形成天然气水合物的实验研究情况．     

大牛地气田产水层段的识别

鄂尔多斯盆地大牛地气田属于低孔、低渗气藏,储层非均质性强,在开发中普遍见水,气井产水对生产和测试会产生很大的不利影响。由于水的存在,有时可能形成天然气水合物,堵塞地层或管线,可能使井筒附近气相的相对渗透率降低,可能在井筒内产生积液,降低气井产量,甚至压死气井,还会使试井曲线出现异常。因此识别出大牛地气田水层的分布对油田的稳定开发有着重大的意义。本文综合试气资料、地质资料、气井的测井响应特征,总结出水层识别的电性标准,对生产实践有一定的指导意义。     

大产液量水平气井不同气举方式气液两相流研究

连续气举是产水量大的水平气井重要排采措施,针对现场正举和反举的特点,为揭示气田开发过程中反举条件下油管和正举条件下油套环空内的气液两相流流动规律,分别用水和空气在套管内径为127.3mm、油管外径为73mm的油套环空和内径为60mm的油管内进行了井筒气液两相管流模拟实验,对低压积液气井气举时井筒流动规律进行了研究分析,分析了井筒中气相和液相的体积流量、注气方式等因素对井筒压降和持液率的影响。实验结果表明,在相同气、液流量条件下,反举时的持液率比正举持液率小;不同气举方式下的井筒压降随注气量的增加呈不同的变化趋势,反举时的井筒压降比同工况下正举的压降大,对于产液量较大且有一定地层能量的气井,推荐采用反举方式进行气井排水采气。     

气体组分变化对油井水合物生成温度的影响

近年来对于气井井筒水合物生成研究甚多,而对油井水合物的生成研究则较少,且由于在重力作用下油相将气、水两相隔开给水合物生成条件测试造成了困难。为此,将测定油气水三相水合物生成问题转化为原油脱出气与水生成水合物的问题,首先开展了油气水三相水合物生成条件测试实验,并以此为基础评价优选出了适用的水合物生成条件预测模型;然后结合油藏流体相图和井筒压力温度预测方法及采出井井流物天然气组成的动态相态数值模拟预测,讨论了天然气组成含量随井深的变化规律;最后采用井口、井深1 000 m和井深1 900 m处组分数据预测了井筒水合物生成温度剖面,验证了气体组分变化对井筒水合物生成温度的影响。实验及计算结果表明:不同含水率对水合物的生成条件并无影响,各模型中简化牛顿热力学模型误差为7.31%,预测精度相对较高;随井深增加,轻烃逐渐下降,重组分逐渐增大;最后指出,采用组分数据预测油井水合物生成温度剖面时,其数据选择尤为重要,否则可能导致预测的准确性降低。该研究成果对于准确预测油井水合物的生成条件具有重要的意义。     

塔里木油田深井开采水合物防治技术研究

油气开采中,水合物的产生会严重影响正常生产,塔里木油田在深井油气开采过程中就出现水合物堵塞现象。本文对水合物生成机理进行研究,基于热力学方法建立了水合物生成预测模型;通过分析各种防治技术的适应性,结合塔里木油田的实际情况,筛选出较好的井下节流技术。根据井筒温度、压力的变化可以对气井井筒中水合物的形成位置进行准确的预测,给出了井下节流技术工艺参数设计模型和方法,可设计出井下节流器位置深度及尺寸,防止水合物的产生,该技术在塔里木油田进行了现场应用,取得了良好效果。     

井筒气液两相流水击波速计算图版的研制与应用

为描述气井关井瞬间或产量调整过程中井筒压力波的变化,通过分析气井井筒水击产生机理,根据动量守恒定律和物质平衡原理,建立井筒气液两相流的水击波速计算模型。水击波速与流体各相的体积含量、流体密度、弹性模量、油管内径、油管壁厚等参数相关。通过分析主要参数对水击波速的影响,提出水击波速标准图版的绘制方法并绘制出水击波速图版,该图版能够查询井筒气液两相流在不同温度、压力和含水率下的水击波速。应用表明,水击波速图版查值与实测值平均误差为2.27%,能够精确地反映水击压力波速度大小,适合在水击参数计算中推广应用。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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